Performance enhancement in coal fired thermal power plants. Part II: Steamturbines

This paper presents the results of the performance enhancement study on 22 coal fired thermal power stations of capacities 30-500 MW. The oldest units (30 MW) have served for 33 yr and the newer units (500 MW) have been in op eration since 7 yr. The turbine efficiencies are in the range 31.00-41.90% as compared to the design range of 34.80-43.97%. The isentropic efficiencie s are in the range 74.13-86.40% as compared to design values of 83.20-89.10 %. Considerable scope for efficiency improvement through low cost solutions: o perational optimization, capital overhaul, simple modifications, etc., exis ts for all classes of units. The efficiencies can be restored to their desi gn values. The developments in turbines over the last quarter of this century which ha ve led to improved isentropic and thermal efficiencies must be adopted for existing units through retrofits, upgrades and revamps. The turbine efficie ncies can be improved to 38.0% for 30 MW units and to 47% for 500 MW units. The maximum potential is for improvement in 210 and 500 MW units followed by 110 and 120 MW units. The potential for 30 and 62.5 MW units is rather l imited because of their low capacity share, lack of interest in manufacture rs to sell spares (because of the low volume of requirement) and large pay back periods for modernisation schemes. Copyright (C) 1999 John Wiley & Son s, Ltd.